1. Field of the Invention
The present invention relates to a laser optical system for a head lamp; and, particularly, to a laser optical system for a head lamp, which can increase optical efficiency through minimization of a light loss and can heighten design degree of freedom through reduction of a size of the optical system.
2. Description of Related Art
A head lamp (headlight) of a vehicle is a lamp that illuminates a front area to secure a driver's front visual field, and halogen, HID (High Intensity Discharge), or an LED diode has been generally used as a light source.
However, since the halogen, HID, or LED diode has high power consumption, the optical efficiency thereof is lowered. In particular, since the overall size of an optical system including a light source and a lens is large, the design degree of freedom becomes low and the weight of the optical system becomes heavy.
Recently, development of a head lamp that uses a laser diode, which is environment friendly and has long lifespan and high optical efficiency, as a light source is on an increasing trend. 
As illustrated in FIG. 1, a laser optical system for a head lamp in the related art is configured to include a laser diode 1 generating a laser beam of a blue wavelength band, a yellow phosphor 2 reacting on light emitted from the laser diode 1 to output white light, a reflective body 3 reflecting the white light output from the phosphor 2 to a front area, an aspheric lens 4 positioned in front of the reflective body 3 to condense, diffuse, and apply the white light that is reflected through the reflective body 3 to the front area, and a shield 5 positioned between the reflective body 3 and the aspheric lens 4 to implement a low beam.
However, according to the configuration of the laser optical system in the related art as described above, the light emitted from the laser diode 1 is incident to the phosphor 2 to be excited, and then is output to the front area where the aspheric lens 4 is present by reflection through the reflective body 3. Accordingly, since the front area of the reflective body 3 is opened to output the white light, a light loss section A1, in which the light emitted from the laser diode 1 is excited by the phosphor 2 and then is emitted out of the reflective body 3, occurs, and thus the light loss of the optical system is generally increased to cause the optical efficiency to be decreased.
That is, the structure in the related art is configured to use the reflective body 3 for forward emission of the white light, and if the reflective body 3 is used, the light loss section A1, in which the white light is emitted out of the reflective body 3, occurs, and thus the light loss of the optical system is generally increased to cause the optical efficiency to be decreased.
Further, since the reflective body 3 having a large volume is used, the weight of the optical system becomes heavy, and the size of the optical system is increased. Accordingly, the design degree of freedom becomes disadvantageous, and further the manufacturing cost is increased.
The information disclosed in this Background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.